servo’s overall torque will be less than
if these values were maximized. Ensure
that these values are maximized and
always mechanically adjust a linkage
to ensure proper control stick and
deflection movement.

To test the performance from a
servo or servos, fly the aircraft to a
moderate altitude and perform rolls at
the highest possible rate. Increase and
decrease throttle input so the flight
speed drastically changes in flight. If
the roll rate decreases as the flight
speed increases, the same deflection is
inconsistent at different flight speeds.

It is important that no matter at what
speed the aircraft is being flown, the
rotation rate is the same. I have seen
pilots utilize excessive control-surface
deflection amounts and improper
application of control inputs, resulting in
over-rotation and under-rotation of the
snap roll, as well as the aircraft changing
heading after the snap roll is performed.

Many pilots prefer to apply full
deflection on all control surfaces, which
results in a tumble-like snap roll that
is difficult to begin and complete at a
desired heading. The aircraft typically
will not be in the correct orientation
with respect to pitch and yaw. Although
you might be able to control a complete
positive or negative snap roll using this
control technique, it will be difficult to
precisely perform a partial snap roll.

I have also seen pilots decrease the
amount of control surface deflection
to make the aircraft easier to stop
after performing the desired number
of snap roll rotations. Having a roll
rate that is too slow might result in a
judge questioning whether the aircraft
was stalled and if the airplane actually
performed a snap roll.

Closing Thoughts

Partial snap rolls are often difficult
to perform because so many different
control inputs must occur in a short
time. For these reasons, it is important to
ensure that the aircraft’s physical setup
is flawless and yields consistent results so
the pilot can focus on each maneuver.

For additional information about the
other criteria on which the snap roll is
judged, consult the AMA Competition
Regulations for Radio Control Scale
Aerobatics, feel free to write to me with
questions, or seek the advice of a fellow
experienced competitor. Above all, enjoy
all aspects of this amazing hobby.